This invention relates to an electronic musical instrument, and more particularly an electronic musical instrument in which musical tone signals stored in a musical tone data memory device and relating to a musical tone are read out according to the depression of a key of the keyboard of the musical instrument so as to produce a musical tone having the tone pitch corresponding to the depressed key.
An electronic musical instrument has been proposed as disclosed in German Pat. No. 2,715,510, for example, in which a musical tone signal having a plurality of periods from the start to the end of a musical tone applied from outside is sampled with a predetermined sampling period by a sampling signal, the amplitudes of the musical tone signal at respective sampling points are stored in respective storage positions of a musical tone data memory device and thereafter the stored musical tone signals are sequentially read out as a key is depressed, thereby forming a musical tone having a tone pitch corresponding to the depressed key.
This prior art electronic musical instruments, however, is constructed such that each of the amplitudes of the musical tone signal stored in the musical tone data memory device are accessed in a predetermined order to read out and reproduce the stored musical signals with high fidelities so that the tone color of the produced musical tone is not different from the tone color of the musical tone applied from outside.
Furthermore, with this prior art electronic musical instrument, when the musical tone signal stored in the musical tone data memory device are read out in response to a key depression, the musical tone signal is read out by an address signal progressing at a speed in proportion to the tone pitch of the depressed key, so that although it is possible to produce a musical tone having the pitch corresponding to the depressed key, there exists a disadvantage in that the interval of the musical tone generation from an attack to the termination of a decay varies depending upon the variation in the tone pitch of the depressed key. In other words, when the tone pitch of the depressed key is increased by one octave, the musical tone data memory device would be accessed by an address signal progressing at twice speed so that the musical tone producing interval from the attack to the end of the decay would be decreased to one half.